1. Field of the Invention
The present invention generally relates to the storage of digital data signals in optical data storage media. More particularly, the invention concerns the storage of digital data signals to an optical data storage medium with minimal power consumption, achieved by adjusting the advancement rate of the optical medium in response to the amount of data to be written, and by establishing a minimum laser write power level necessary to achieve a desired level of write effectiveness under the adjusted advancement rate.
2. Description of the Related Art
It is generally desirable to advance digital data recording media as fast as possible during read and write operations. "Advancing" disc media refers to the rotation of the disc, whereas advancing tape media refers to the movement of the tape from a source reel to a take-up reel.
Advancing the media at a higher rate increases the "effective data rate." When reading data from the media, having a faster advancement rate translates into reading data more quickly, e.g. more bits per second. Analogously, having a faster advancement rate when writing data to the media translates into writing data more quickly. However, in optical storage drives where a laser writes data to a disk, greater advancement rates demand that the laser be operated at a higher power level. Unfortunately, this reduces laser life.
Some known systems are said to adjust optical laser write power while writing to optical disc media. See, for example, U.S. Pat. No. 5,390,162 to Fukumoto et al. and U.S. Pat. No. 5,134,606 to Sekiguchi et al. In the '162 patent, for example, a magneto-optical disk is rotated at a constant angular velocity, and a detecting unit detects the radial position of the magneto-optical disk. The laser power and external magnetic field are controlled depending on the output of the detecting unit to keep the size of an effective reproducing region constant without regard to the linear velocity at each reproducing position. The '162 disclosure therefore seeks to vary laser power to automatically to account for the increasing linear velocity that occurs at outer radial regions of the disk. This is apparently performed to ensure that adequate write laser power is supplied, at such regions, where the linear velocity is faster. Although this approach purports to maintain uniform laser write effectiveness, it still does not address the need of some users to minimize power usage in optical storage drives. Other known approaches are similarly lacking.